Should the past remain the past when terrorists are involved?

Americans should never forget that some of them supported the IRA with cash and arms killing British soldiers who were surposed to be their allies. The IRA were not "cool" as they were just as bad as the 9/11 terrorist who were hell bent on killing innocent civilians. I know as one of my sons was nearly killed by them. Having said that I do not blame all Americans as it was mostly supported by the misguided Irish Americans.